1. Field of the Invention
The present invention relates to wireless communications, and more particularly, to a method and apparatus for Multimedia Broadcast/Multicast Service (MBMS) in a wireless communication system.
2. Related Art
3rd generation partnership project (3GPP) long term evolution (LTE) is an improved version of a universal mobile telecommunication system (UMTS) and is introduced as the 3GPP release 8. The 3GPP LTE uses orthogonal frequency division multiple access (OFDMA) in a downlink, and uses single carrier-frequency division multiple access (SC-FDMA) in an uplink. The 3GPP LTE employs multiple input multiple output (MIMO) having up to four antennas. In recent years, there is an ongoing discussion on 3GPP LTE-advanced (LTE-A) that is an evolution of the 3GPP LTE.
A multimedia broadcast/multicast service (MBMS) is a service which provides multimedia traffic to a user equipment (UE) in a cell. In the 3GPP LTE, the MBMS is provided through a multicast channel (MCH) which is a common transport channel in order to increase efficiency of a radio resource, and a plurality of MCHs can be used in one cell according to capacity of a multicast traffic channel (MTCH) and a multicast control channel (MCCH). The MCH serves to transmit two types of logical channels, i.e., the MTCH and the MCCH, and is mapped to a physical multicast channel (PMCH) which is a physical channel.
Only one MCCH exists in each cell, and the MCCH is a control channel used for transmission of MBMS control information. In order for the UE to receive traffic data of a certain MBMS, the MCCH for transmitting the control information of the MBMS has to be received. This is because scheduling information regarding the MTCH for the MBMS is transmitted on the MCCH. The UE first receives the MCCH to acquire information regarding an MTCH for transmitting the MBMS desired by the UE and then receives the MTCH.
As a plurality of MBMSs is simultaneously provided, the UE can receive the MBMS on an MCH in which only MTCHs are multiplexed. How to receive an updated MCCH by the UE on the MCH in which only MTCHs are multiplexed is not introduced yet.